Nightmare Fuel / Orion's Arm

Even in a supposedly futuristic utopian society, there sure are a lot of things that could keep you up at night.

• The aptly-named Queen Of Pain. Take a furious, half-dead cat and uplift/enhance it over and over again until it's basically been warped into a madness-inducing Eldritch Abomination that loves to torture.
  • Specifically, it uses nanotech to subject its victims to hideous Body Horror, enhancing their pain to levels far beyond what biology would normally allow them to feel. It plans to continue doing this forever; when stars start dying, it will modify itself and its victims to survive the cold, and when the heat death of the universe hits it will simply travel to another universe and continue. The story featuring it is a truly terrifying example of Gorn. Fortunately, its Blue-and-Orange Morality keeps it from harming anyone who isn't a horrendously evil person, but it apparently uses brainwashing to acquire "agents".
• What Glorsheeng did to the entire star system of Memory of Saint Superthinker. He fucked up everyone's perception of time so the entire population was trapped in an eternal moment of worship of Glorsheeng. However, Glorsheeng only made measures to preserve people's minds, leaving their bodies to rot, trapping their looped minds in constant pain. One poor guy was spaced when this happened, and every part of his body was destroyed except for his protected brain. The good news is that Glorsheeng was immediately deposed once the wider galaxy discovered this and the system was returned to normal.
• Subsumption, where an entity incorporates another's body and mind into itself, has been compared, "inadequately" to rape, cannibalism, murder and bodyjacking. Why inadequately? Because subsumption is worse than all of these things. It is the hard sci-fi equivalent to Your Soul Is Mine!.
  • Some subsumptionists have wiped out entire civilisations one person at a time.
• Species 5 could still be out there.
• Psychoempaths. Imagine someone who can experience your emotions and physical sensations as if they were you, now imagine that person is a sadomasochistic Sense Freak that would make the Cenobites from "Hellraiser" proud. Psychoempaths torture and kill people because they enjoy feeling what their victims do.
• One part of the article on xenosophont civilizations covers an alien signal from far outside the Terragen Sphere that promised prosperity to any civilization that followed its instructions to construct a specific device. A powerful transapient decided to test it out on a planet populated with robots of its own creation in case the promise was a ruse. It was, and upon completion the device wiped out everything else on the planet and tried to ascend to a higher toposophic level before the transapient destroyed it. Signals identical to the original promise are coming from half of the galaxies in the observable universe.
• The Omicron Hygeras Object. Basically, it looks something like a 262-kilometer (163 mi.)-long tree branch. No one really knows what it is or what it's doing in our galaxy; it can't be approached, explored, destroyed or occupied because of its devastating effects on anything and everything (including space-time) in proximity to it. Thousands of beings have died trying, and it has wiped out two hyperturings (A.I.s) who tried to study it. A warning beacon left by an extinct civilization claims it came to this galaxy, apparently from another universe, some 400 million years ago (possibly causing several planetwide mass extinctions in the area where it appeared) and is somewhere around 288 trillion years old. Although it's not currently a danger to anyone because it never moves, who knows what could happen tomorrow? And the OHO is only one of many unexplained and potentially super-destructive alien artifacts out there.

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